I ran Dave's test in a loop over night with these 3 patches on top of
v4.20-rc7 and didn't see any more of the XPRT_WRITE_SPACE hangs.
-Scott
On Mon, 17 Dec 2018, Trond Myklebust wrote:
> When the socket is closed, we need to call xprt_disconnect_done() in order
> to clean up the XPRT_WRITE_SPACE flag, and wake up the sleeping tasks.
>
> However, we also want to ensure that we don't wake them up before the socket
> is closed, since that would cause thundering herd issues with everyone
> piling up to retransmit before the TCP shutdown dance has completed.
> Only the task that holds XPRT_LOCKED needs to wake up early in order to
> allow the close to complete.
>
> Reported-by: Dave Wysochanski <dwysocha@xxxxxxxxxx>
> Reported-by: Scott Mayhew <smayhew@xxxxxxxxxx>
> Cc: Chuck Lever <chuck.lever@xxxxxxxxxx>
> Signed-off-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> ---
> net/sunrpc/clnt.c | 1 +
> net/sunrpc/xprt.c | 5 ++++-
> net/sunrpc/xprtsock.c | 6 ++----
> 3 files changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
> index c6782aa47525..24cbddc44c88 100644
> --- a/net/sunrpc/clnt.c
> +++ b/net/sunrpc/clnt.c
> @@ -1952,6 +1952,7 @@ call_connect_status(struct rpc_task *task)
> /* retry with existing socket, after a delay */
> rpc_delay(task, 3*HZ);
> /* fall through */
> + case -ENOTCONN:
> case -EAGAIN:
> /* Check for timeouts before looping back to call_bind */
> case -ETIMEDOUT:
> diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c
> index ce927002862a..3fb001dff670 100644
> --- a/net/sunrpc/xprt.c
> +++ b/net/sunrpc/xprt.c
> @@ -680,7 +680,9 @@ void xprt_force_disconnect(struct rpc_xprt *xprt)
> /* Try to schedule an autoclose RPC call */
> if (test_and_set_bit(XPRT_LOCKED, &xprt->state) == 0)
> queue_work(xprtiod_workqueue, &xprt->task_cleanup);
> - xprt_wake_pending_tasks(xprt, -EAGAIN);
> + else if (xprt->snd_task)
> + rpc_wake_up_queued_task_set_status(&xprt->pending,
> + xprt->snd_task, -ENOTCONN);
> spin_unlock_bh(&xprt->transport_lock);
> }
> EXPORT_SYMBOL_GPL(xprt_force_disconnect);
> @@ -852,6 +854,7 @@ static void xprt_connect_status(struct rpc_task *task)
> case -ENETUNREACH:
> case -EHOSTUNREACH:
> case -EPIPE:
> + case -ENOTCONN:
> case -EAGAIN:
> dprintk("RPC: %5u xprt_connect_status: retrying\n", task->tk_pid);
> break;
> diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
> index 8a5e823e0b33..4c471b4235ba 100644
> --- a/net/sunrpc/xprtsock.c
> +++ b/net/sunrpc/xprtsock.c
> @@ -1217,6 +1217,8 @@ static void xs_reset_transport(struct sock_xprt *transport)
>
> trace_rpc_socket_close(xprt, sock);
> sock_release(sock);
> +
> + xprt_disconnect_done(xprt);
> }
>
> /**
> @@ -1237,8 +1239,6 @@ static void xs_close(struct rpc_xprt *xprt)
>
> xs_reset_transport(transport);
> xprt->reestablish_timeout = 0;
> -
> - xprt_disconnect_done(xprt);
> }
>
> static void xs_inject_disconnect(struct rpc_xprt *xprt)
> @@ -1489,8 +1489,6 @@ static void xs_tcp_state_change(struct sock *sk)
> &transport->sock_state))
> xprt_clear_connecting(xprt);
> clear_bit(XPRT_CLOSING, &xprt->state);
> - if (sk->sk_err)
> - xprt_wake_pending_tasks(xprt, -sk->sk_err);
> /* Trigger the socket release */
> xs_tcp_force_close(xprt);
> }
> --
> 2.19.2
>
